Concentric pipe insulator and spacer



sept. 9, 1952 INVENTOR. DONA LD H BOND 3y/@M A TTORNEYS Ressued Sept. 9, 1952 coNcsNralc mrs m'sumron smi srscsa Donald H. Bond, Houston, Tex., assigner to The Texas of Delaware Company, New York. N. Y.. a corporation original No. 2.55am. usted my s. im. sel-m No. 773.885,".eptelnber 13, 1941.

May l, 1953, Seda] N0. $85,485

for reissue Application 9 Claiml. (CL 13B-.85)

Matter enclosed in heavy brackets I: :I appears iu the original patent but forms no part of this reissue specification; matter printed in italica indicates the additions made .by reissue.

inner pipe when the inner' pipe is drawn orv pushed within the outer pipe.

In the construction of pipe lines for conducting oil and the like, it is the present practice in many instances to place the oil conducting pipe within an outer pipe or casing and to electrically insulate the pipes from each other throughout their lengths. Due to such insulation it has been found possible to greatly'reduce the power requirements when cathodic protection is applied to the pipe line involved, for preventing corrosion thereof.

Various attempts 4have been made to provide insulators and spacers for this purpose, but in most cases, the material used has either not been a sufficiently good electrical insulator, or the devices have not been suiiiciently rugged to stand up when the inner pipe lengths are pulled within the outer casing.

In accordance with the invention, a plurality of sets or groups of insulator or spacer members are firmly securedin spaced relation around the outside surface of the inner pipe, and these members are formed of a material which has a high dielectric and mechanical strength with low moisture absorption properties such as Bakelite. The inner pipe is normally coated with a layer of perhaps V8 thickness of a material such as asphaltum, felt or kraft paper. It is preferred that any outer felt or kraft paper coating be removed and replaced with another coating of about three layers of fiber glass at those places where the groups of spacer elements are positioned. In one group any desired number of the elements may be used and it has been found that where the inner pipe is from say 4 to 8" in diameter, six Velements per group are satisfactory. Each of the elements is square'or rectangular in cross-section and may vary in length depending upon the sizes of pipe involved. 'I'he elements are placed around the ilber glass coating on the inner pipe in uniformly separated relation with their longitudinal axis parallel to the longitudinal axis of the pipe.

The elements are preferably maintained in poattached thereto, or the ends of rods may be threaded and when cooperating nuts are tightened on the alternately arranged rods the elements in a group will be pulled tightly toward the surface of the inner pipe. The outer surface or edge of eachof the elements is preferably tapered'towardsthe inner pipe so that when at- .tached, the groups of elements will act as sled runners to permit relative lengthwise movement between the inner and outer pipes.

For a better understanding of the invention, reference may be had to the accompanying drawinginwhich:

Fig. 1 is a cross-section through a group of spacer elements in place between an inner pipe and its outer casing;

Fig. 2 is a longitudinal cross-section on the line 2-2 of Fig. 1 and,

Fig. 3 is a longitudinal view partly in section, showing two groups of the spacer elements in place.

Referring to the drawing, a' pipe III which may be a length of an oil pipe line, for example, is coated with a layer I2 of a material such as asphaltum and/ or kraft paper. The inner pipe Il is axially disposed within an outer pipe or casing Il which may rest upon orbe buried in the earth.

At desired intervals a throughout the length of the pipe, the outer paper coating I2 is removed and replaced, preferably with a coating Ii consisting of about three layers of fiber glass. A number of groups or sets of insulating and spacing elements Il are disposed at intervals throughout the length of the pipe and as shown in the drawing, each group consists of six uniformly spaced elements.

Each of the elements i8 is formed of an elongated bar of a material having a high dielectric and mechanical strength with low moisture absorption properties such as, for example, the phenolic condensation product, Bakelite, and may be rectangular in cross-section, and several inches in length. The height of each element is substantially equal to or very slightly less than the distance between the outer surface of the fiber glass coating I6 and the limer surface of the casing I4. A plurality of rods or bars 2l serve to hold the elements in place, each of these bars being more or less U shaped and having .riphery or said inner pipe.

absorption properties,

' drawing the rods oi' disposed laterally on which nuts Il ai adapted to bwrewd- As shown more cl'e'arlyin Fig. 1, each ofthe alemeits pfpn'e of 'each group is provided 'with four holes bdagted to actommdat'e the end :portions oi' four of t erod's 2I, while the remaining elements are provided with 'two holes each. l: desired. the roes n may be roi-ced through the holes in the elements and then bent to Ith'e 'c'o i tion shown in Fig. 1 or if desired the elements may be molded about the pre-formed rods. 'I'he rods 2l are arranged in alternating relation as shown in Fig. 3. When the nuts 22 are tightened, the elements of a group will be drawn towards the center of the inner pipe and will be clamped ilrmly against the coating I6. With this arrangement there Iwould be little likelihood that the elements will twist or ,become loose. Each ofthe elements is provided with tapered ends 24 so that each serves as a sled runner when the inner pipe Il is pulled within the outer casing Il. With this arrangement the groups oi' elements oer little it any resistance when the ixmer pipe is pulled or pushed into the casing. It has been found that for the distance a between the spacer groups, feet is satisv a coating oi electrically insulating material factory, although this may of course vary, de-

pending uponthe size oi the pipes I0 and IlY and the weight of pipe I0.

Instead of the more or less rigid bars 2D,

lengths of cable may be used, the ends of the cable lengths being provided with threaded caps or other suitable means for attachment of the nuts 22.

Obviously many modifications and variations of the invention, as hereinbeiore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

l. A device i'or uniformly spacing and'electrically insulating an inner fluid conducting pipe from an outer pipe casing comprising a plurality of elongated spacer elements disposed in parallel to and in separated relation about the peeach of said elements being i'ormed of a material having a high dielectric and mechanical strength and low moisture means for rigidly ciamping said elements to` said inner pipe, said means comprising a plurality of U shaped rods disposed laterally through said elements `and `arranged in pairs in opposing relation about opposite sides of said inner pipe, and means for each pair toward each other to tighten said elementsagainst the inner pipe.

2. A device for uniformly spacing and electrically insulating anj inner uid conducting pipe from an outer pipe casing comprising a vplurality of elongated spacer membersV disposed in par-l allel to and in separated relation about the periphery of said inner pipe, each of said members being formed of a material having a high dielectric and mechanical strength and low moisture abmrption properties, means for rigidly clamping said members to said inner pipe, said means comprising a plurality of elements through said members and arranged in pairs in opposing relation about opposite sides of said inner pipe. and means for drawing the elements of each -pair toward each other to tighten said members against the inner pipe.

3. An assembly for a pipe line comprising an a1le1 to and in separated outer pipe casing, an inner fluid conducting pipe.

around and in contact with a portion of said inmeans for centrally spacing and elecand means for clamping said members tightly against said pipe coating in said separated relation. said means comp a plurality oi elements disposed laterally through said members and arranged in pairs in opposing relation about opposite sides of said inner pipe, and means for drawing the elements of each pair toward each other to tighten said members against the inner pipe.

4. A device according to'claim 2 in which the end portions of the spacer members taper toward said inner pipe, themaximum height of each element being substantially equal to the distance of the outer surface ci the inner pipe and the inner surface of the outer casing.

5. An assembly according to claim 3 in which A spacer members taper the end portions of the toward said inner pipe to provide runners so that the inner pipe with the spacer members clamped thereto can be readily pulled or pushed within the outer casing.

6. A device for uniformly spacing and electrically insulating an inner fluid conducting pipe from an outer pipe casing comprising a plurality of elongated spacer members disposed in parrelation about the periphery of said inner pipe, each of said members being formed of amaterial having a high dielectric and mechanical strength and low moisture absorption properties, means for rigidly clamping said members to said ixuier pipe. said means comprising a plurality'of elements arranged in pairs in opposing relation about the opposite sides of said inner pipe and connecting members. and means of each pair toward members against the ity of elongated spacer members disposed in separated relation about the periphery 01'. and parallel to, the longitudinal axis oi' said inner pipe, each ci' said members being formed of a material about opposite sides of said inner pipe and connecting laterally with said spacer members. the point of connection being substantially removed from the surface of contact between said spacer members and the inner periphery ot the outer allel to and in separated relation about the e-` riphery of said inner pipe, p

at least some of said a material having a members being formed of dielectric and mechanical strength and low high moisture absorption. and means for clampina said members tightly to said inner pipe, said means comprising a plurality of elements disposed laterally through said members and arranged about the inner pipe. one of said members being provided with spaced lateral apertures, the end portions of said elements passing oppositely through said apertures and means for tensioning the said end portions against opposite lateral faces of the said member to tighten said members against the inner pipe.

9. A device for uniformly spacing and electrically insulating an inner )luid-containing pipe from an outer pipe casing comprising a plurality o! elongated spacer members disposed in parallel toand in separated relation about the periphery of said inner pipe. each of said members comprising a material having a high dielectric strength and low moisture absorption, and means for clamping said members tightly to said inner pipe. said means comprising a plu'- rality of elements disposed laterally through said members and arranged about the inner pipe, the end 'portions of said elements passing latlthereby drawing said elements together to tighten said members against said inner pipe.

DONALD H. BOND.

REFERENCES CITED The following references are of record in the file oi this patent or the original patent:

' UNITED kSTATES PATENTS of said members in 

